In the field of optical communication, an optical switch is used for changing over an optical fiber transmission path or a light transmission/reception terminal device or the like. Views shown in FIG. 1(a) and FIG. 1(b) are a plan view and a cross-sectional view for explaining the structure of a main part of a 2×2 type optical switch which has been proposed conventionally. In this optical switch, a recessed portion 3 is formed in a flat-panel like switch board 2 and a first and second light reflection surfaces 4, 5 are formed on inner surfaces of the recessed portion 3 such that these reflection surfaces 4, 5 make an angle of 90 degrees. Further, an elongated resilient member 6 is formed on a bottom surface of the switch board 2 in a cantilever manner, wherein a distal end of the resilient member 6 having resiliency is fixed to a cubic movable reflection member 7. The movable reflection member 7 is arranged to be positioned in an inner corner portion constituted by the first and second light reflection surfaces 4, 5. Further, a third and fourth light reflection surfaces 8, 9 are formed on two neighboring surfaces of the movable reflection member 7. The resilient member 6 is configured, as shown in FIG. 1(b), bendable in the up-and-down directions and the movable reflection member 7 which is positioned in the inner corner portion of the first and second light reflection surfaces 4 is lowered more downwardly than the first and second light reflection surfaces 4, 5 along with the downward bending of the resilient member 6. Although not shown in the drawings, an electromagnet is arranged below the switch board 2, wherein when the electromagnet is energized, the resilient member 6 is attracted downwardly and hence, the movable reflection member 7 is lowered downwardly, while when the electromagnet is deenergized, the resilient member 6 is attracted upwardly and hence, the resilient member 6 returns upwardly whereby the movable reflection member 7 returns in front of the first and second light reflection surfaces 4, 5.
FIG. 2(a), (b) are views for explaining the changeover operation of the above-mentioned optical switch. In this example, a first input optical fiber 10 is arranged to face the first light reflection surface 4 in an opposed manner, a second input optical fiber 11 is arranged to face the fourth light reflection surface 9 in an opposed manner, a first input optical fiber 12 is arranged to face the third light reflection surface 8 in an opposed manner, and the second input optical fiber 13 is arranged to face the second light reflection surface in an opposed manner.
Here, when the movable reflection member 7 is elevated and is positioned in front of the first and second light reflection surfaces 4, 5, as shown in FIG. 2(a), a light 14 radiated from the first input optical fiber 10 is reflected on the first light reflection surface 4 and the third light reflection surface 8 and, thereafter, is coupled to the first output optical fiber 12. A light 15 radiated from the second input optical fiber 11 is reflected on the fourth light reflection surface 9 and the second light reflection surface 5 and, thereafter, is coupled to the second output optical fiber 13.
Further, when the movable reflection member 7 is lowered and is not positioned in front of the first and second light reflection surfaces 4, 5, as shown in FIG. 2(b), the light 14 radiated from the first input optical fiber 10 is reflected on the first light reflection surface 4 and the second light reflection surface 5 and, thereafter, is coupled to the second output optical fiber 13. The light 15 radiated from the second input optical fiber 11 is reflected on the second light reflection surface 5 and the first light reflection surface 4 and, thereafter, is coupled to the first output optical fiber 12.
Accordingly, in the optical switch having such a constitution, by elevating and lowering the movable reflection member 7 by driving the resilient member 6 with the electromagnet, the coupling destinations of the lights radiated from the first input optical fiber 10 and the second input optical fiber 11 can be changed over between the first output optical fiber 12 and the second output optical fiber 13.
However, in the optical switch having such a structure, since the first and second light reflection surfaces 4, 5 and the third and fourth light reflection surfaces 8, 9 are formed on different members (inner surfaces of the recessed portion of the switch board 2 and the movable reflection member 7), in an assembling step of the optical switch and at the time of coupling the optical switch and the optical fiber, the positioning of the respective light reflection surfaces and the optical fiber becomes extremely cumbersome and hence, these operations become difficult to perform.
To explain the above more specifically, it is as follows. First of all, in a state before mounting the movable reflection member 7 on the resilient member 6, the first and the second input optical fibers 10, 11 and the first and the second output optical fibers 12, 13 are arranged parallel to each other and, thereafter, as shown in FIG. 2(b), the positions of centers of four optical fibers 10, 11, 12, 13 are aligned with each other for every combination of inputting and outputting of lights such that the light 15 which is radiated from the second input fiber 11 is incident on the first output optical fiber 12 and the light 14 which is radiated from the first input optical fiber 10 is incident on the second output optical fiber 13 and, in a post center-alignment state, the respective optical fibers 10, 11, 12, 13 are fixed by solidifying them with an adhesive agent or the like. Next, the movable reflection member 7 is arranged in front of the second input optical fiber 11 and the first output optical fiber 12 and a position and an angle of the movable reflection member 7 are adjusted by moving the movable reflection member 7. As shown in FIG. 2(a), when the position and the angle of the movable reflection member 7 are adjusted with respect to the respective optical fibers 10, 11, 12 and 13 such that the light 14 radiated from the first input optical fiber 10 is incident on the first output optical fiber 12 and the light 15 radiated from the second input optical fiber 11 is incident on the second output optical fiber 13, the movable reflection member 7 is fixed to an upper surface of the distal end portion of the resilient member 6 using an adhesive agent or the like while holding the state.
However, in the state that the movable reflection member 7 is not yet mounted on the resilient member 6, the centers of the respective optical fibers 10, 11, 12 and 13 are aligned with each other and, thereafter, the respective optical fibers 10, 11, 12 and 13 are fixed. Accordingly, in the adjustment of the position and the angle of the movable reflection member 7 in front of the optical fibers 11, 12, the positional relationship among the optical fibers 10, 11, 12 and 13 cannot be changed and hence, it is difficult to adjust the position and the angle of the movable reflection member 7 with high accuracy. Further, when there exist irregularities with respect to the positions of the first light reflection surface 4 and the second light reflection surface 5, there also arise the irregularities with respect to the positions of the optical fibers 10, 11, 12 and 13 which are determined by reference to the light reflection surfaces 4, 5 and hence, the adjustment of the position and the angle of the movable reflection member 7 become further complicated. Accordingly, with respect to the optical switch having such a structure, before and after mounting the movable reflection member 7, it is necessary to adjust the positions of the optical fibers 10, 11, 12 and 13 and the position and the angle of the movable reflection member 7 in a trial-and-error manner thus making the assembling of the optical switch difficult.